OBJECTIVE. Infants who are younger than 6 months and have influenza demonstrate significant morbidity and mortality. Trivalent inactivated influenza vaccine is indicated for parents and household contacts of these infants; however, the influenza vaccination rate in this population is estimated at 30%. The objective of this study was to determine the feasibility of trivalent inactivated influenza vaccine administration to parents in a tertiary-care, level III NICU and measure the effect of this program on vaccination rates among parents of this high-risk population.
METHODS. For a 4-month period during influenza season, all parents of admitted patients were informed of the risks and benefits of trivalent inactivated influenza vaccine by placing an information letter at their infant's bedside. All staff were educated about the dangers of influenza and instructed to reinforce the need to obtain vaccination. Parents were screened, provided medical consent, and, when eligible, were immunized at their infant's bedside.
RESULTS. During the study period, 158 children (273 parents) were admitted to the NICU with gestational ages ranging from 24 to 41 weeks; 220 parents (130 infants) were offered the vaccine, and 40 parents received the vaccine from their obstetrician. Overall vaccination rate was 95% (209 parents). A total of 23% of the parent population had never received trivalent inactivated influenza vaccine, despite having previous indications for immunization (smoking, asthma, or other children younger than 23 months, the indicated age for parental vaccination at the time of this study); 75% of the population received trivalent inactivated influenza vaccine for the first time. The 28 infants whose parents were not offered vaccine spent <72 hours in the NICU.
CONCLUSIONS. Administration of trivalent inactivated influenza vaccine in the NICU is an effective means of increasing vaccination rates in parents of this population. In addition, the improved access and convenience allow for an increase in first-time vaccination of parents who were previously eligible to receive trivalent inactivated influenza vaccine but were never immunized.
Influenza is a common infectious agent in the pediatric population, infecting 15% to 42% of preschool children with a fatality rate of 3.8 per 100000.1–3 The majority of these deaths occur in children who are younger than 6 months.4 Recent data demonstrate that this epidemiologic pattern is true irrespective of latitude, and the influenza burden in children with underlying cardiac and respiratory disease is substantial up to 5 years.5 Those with underlying respiratory and cardiac disease are more likely to require hospitalization and more susceptible to morbidity from the disease.6–9
Trivalent inactivated influenza vaccine (TIV) is a safe, cost-effective method of preventing influenza in children, with a seroconversion rate of up to 89%.10–12 At the time of this study, both the American Academy of Pediatrics and the Advisory Committee on Immunization Practices recommend that influenza vaccine be administered to household contacts and out-of-home caregivers of infants from 0 to 6 months of age.13 Also included in this high-risk category are children with chronic respiratory and cardiac disease.10
Immunization rates in the indicated pediatric population are increasing, ranging from 9% to 22%.14 However, immunization rates in adults who are aged 18 to 64 and have high-risk conditions remain low, ∼20% to 33%, a statistic that leaves many preterm infants who are younger than 6 months unprotected from influenza.15,16
Because the majority of adults who meet eligible criteria are not vaccinated, it has been proposed that the NICU begin to administer the influenza vaccine to parents of high-risk infants, eliminating commonly encountered obstacles to vaccine administration.17,18 However, no study to date has demonstrated the feasibility of providing influenza immunization to parents or the effect of such a program on immunization rates. The purpose of the study was to provide influenza immunization in the NICU to parents and observe the effect on vaccine compliance as compared with the 32% baseline rate of immunization in the community at large.
Between November 1, 2005, and March 1, 2006, 273 parents of 158 infants who were hospitalized in the New York University Medical Center NICU were eligible for counseling regarding immunization against influenza with TIV. Signs posted in the NICU asked parents to discuss influenza prevention with their physician. On admission, a letter that was addressed to the parents and included the risks and benefits of immunization and the vaccine information sheet for TIV was placed at the infant's bedside. Before the implementation of the program, nursing staff were educated about the need to immunize parents and to call medical personnel when parents were available at the bedside.
All discussions regarding the risks and benefits of immunization were performed on the basis of a standard outline and included informed consent for administration of TIV. All conversations took place at the bedside of the hospitalized infant, and all parents' questions were answered.
Parents who were considering immunization were given a standardized consent form from New York University Employee Services that asked screening questions to assess contraindications for vaccination (allergy to egg, fever, previous reaction to thimerosal, and a history of Guillain-Barré syndrome.) Vaccine lot number, the name of administering physician, date, and name of infant in the NICU were also recorded.
On completion of screening, parents were administered TIV in the deltoid muscle of the nondominant extremity and were not allowed to leave the NICU for 30 minutes after receipt of vaccine. Parents who refused immunization were given a previously validated open-field questionnaire to determine their medical eligibility for vaccination and their reasons for refusal.
Because all parents of NICU patients are medically indicated to obtain the influenza vaccine, withholding vaccination to a cohort of parents in the NICU to obtain baseline rates of immunization in our NICU parent population was considered unethical by institutional review board standards. Control data were obtained from the Centers for Disease Control and Prevention (CDC) Immunization Surveillance for adults who are aged 18 to 65 and have 1 medically indicated risk factor necessitating influenza vaccination. Historically, this immunization rate has not differed significantly from the rate of NICU parents who obtain vaccination.19
Responses were tabulated into numerical data and were entered into a Microsoft Excel Database (Microsoft Corp, Redmond, WA) along with information regarding the patient's gestational age, length of stay, birth weight, and admission diagnosis based on International Classification of Diseases, Ninth Revision code. Student's t test was used for analysis, and P < .05 was considered significant. Institutional review board approval was obtained before implementation (NYU IRB 11769-02).
Overall Vaccination Rate
During the study period, 158 infants were admitted to the NICU with an average birth weight of 2458 g (range: 675–4420 g) and a gestational age of 33 weeks, 1 day (range: 24 weeks to 42 weeks, 2 days). A schematic outline of the study population is shown in Fig 1. These infants had 273 parents (109 fathers and 111 mothers) with an average age of 34.5 years (range: 15–54 years). During the study period, 220 parents of 130 infants (80.5%) of the admitted population were offered influenza vaccination. Among this group, 71.3% (157 parents) were immunized in the NICU. Eleven (5%) parents of the group refused immunization, and 52 (23.6%) parents received vaccination before their infant's NICU admission; 40 (78%) of these 52 were pregnant mothers who were immunized by their obstetrician. Overall vaccination rate was 94.9% and significantly greater than the 32% control data from the CDC in this population. Of the 157 parents who received TIV in the NICU, 75.5% of them had never received the immunization before, yet 31% of this cohort had previous risk factors necessitating vaccination. Of the remaining 24% who had been immunized in the past, 21% had >1 risk factor for immunization.
Immunization Pattern and Gestational Age
Immunization trends are detailed in Fig 2. All parents of infants who were <32 weeks' gestational age either were immunized before admission or received TIV in the NICU; 8.5% of parents with children between 32 and 36 weeks were not offered immunization, and 3.3% of this cohort refused immunization. For parents with infants >36 weeks' gestation, 5.5% of the cohort refused and 29.6% were not offered immunization. The majority of these missed parents (60%) were admitted for <48 hours before NICU discharge. Comparison of parental vaccination rates for infants who were <36 weeks' gestation with those of older gestational age was significant (P < .02, Student's t test).
Efficiency of Immunization Delivery and Seasonal Variation
Data for the 143 parents who were immunized in the NICU and whose infants were admitted after the start of the program are shown in Fig 3. Across all gestational ages, 61% of parents were immunized within 72 hours of their infant's NICU admission, with ∼20% being immunized each day. Of the remaining 40% of parents, half were immunized on day 3 or 4 of infant hospitalization; 16% of parents received their vaccination ≥6 days after admission. Vaccination rate within the first 72 hours of admission was significantly higher than in the remaining NICU length of stay (P < .05 Student's t test).
Monthly distribution of parents who had received influenza immunization before NICU admission across all gestational ages is shown in Fig 4. In the earlier months of influenza season (November and December), 13% and 17% of parents, respectively, had already received immunization. In January and February, 34% and 31% of parents, respectively, had already been immunized. This represents a statistically significant increase from the previous months (P < .05, Student's t test).
Refusal of Immunization
Eleven parents refused immunization. Their infants averaged 2942 g and were of a significantly older gestation age (37 weeks, 1 day versus 33 weeks, 1 day; P < .04, Student's t test). One parent demonstrated a medical contraindication to vaccination (egg allergy). The most common reason for refusal was a statement that parents “don't believe in” vaccination. One parent cited religious objection, and 1 parent declined vaccination in late February, stating that it was “too late in the season.”
Immunization Effect on Staff
Availability of TIV in the NICU increased health care worker immunization rates by 35%. In the previous year, 32% of staff had obtained TIV immunization outside the NICU. By the end of the influenza season, 67% of 112 NICU health care workers had received TIV; 45% of the entire immunized cohort were immunized in the NICU.
Influenza infection is a leading cause of hospitalization in pediatric patients with underlying illnesses.6 The American Academy of Pediatrics recommends influenza vaccination for individuals who are in close contact with high-risk infants and has expanded vaccination to include parents and first-person contacts of children up to 5 years of age.13,20 As noted, compliance rates among eligible adults remains 25% to 32% and has not changed significantly in the past several years.21 As the population of adults who are required to obtain vaccination on the basis of contact with the pediatric population increases, there is a need for research-based strategies to improve vaccination rates. Administration of TIV to parents in the NICU is feasible and provided a vaccination rate of ∼95% in our study, significantly higher than the 33% rate of adults who are aged 18 to 65 years and have a risk factor for influenza as determined by the CDC. Furthermore, health care worker vaccination increased by 35%, with the greatest increase in immunization rates among nurses, who provide the closest contact with susceptible NICU infants. The program provides direct contact between a high-risk population with the convenience of care at an infant's bedside and the 24-hour availability of critical care staffing, providing ideal conditions for TIV administration.
Delivery of TIV in this manner is not without limitations. Parents of 28 infants (20% of the total parental cohort) were not offered immunization. The majority of these infants were of term gestation and spent <72 hours in the NICU before discharge. Given their age, these children are at high risk for complications from influenza; however, their risk is no different from that of a healthy, term infant and significantly lower than that of a preterm infant with chronic lung disease.4 Logistic and financial considerations regarding who pays for vaccination and who ideally administers TIV also must be resolved.
For improvement of immunization delivery, maximal effort should be placed on vaccinating parents in the first 24 to 28 hours after admission. This may reflect a limitation of vaccine delivery to parents in the NICU given other medical priorities of a neonate on admission. Immunization of only 40 mothers took place before admission to the NICU across all gestational ages. Ideally, maternal immunization is preferable to postnatal administration, because it allows for the passive transfer of maternal IgG antibodies to the fetus. Strategies for improving delivery to the mother before delivery require exploration to increase immunization further.
Other strategies for improving vaccination rates using this delivery model have been suggested,22 such as inclusion of vaccination of parents, particularly fathers, during the prenatal consult before delivery and greater allocation of resources for immunization (ie, personnel) earlier in the season, when parents who enter the NICU are less likely to have received immunization. Nevertheless, given the increased levels of acuity in tertiary-care NICUs, offering influenza vaccine to 80% of parents was feasible and represents a new arena and method of preventive health care delivery. Given the vaccination rate and the ease of implementation, the program is an ideal candidate for newborn well nurseries; however, it is not known how the shorter stays and the relative health of these infants compared with preterm infants will influence vaccination rates.
Other applications of this parental-intervention model include the use of the NICU for smoking cessation, administration of acellular pertussis vaccine to parents, and depression screening.23 Additional multicenter studies are required to determine whether the immunization rate achieved in this program is reproducible in different NICUs and whether this model of health care delivery is sustainable for other public health interventions.
We acknowledge the contribution of the New York City Department of Health and Mental Hygiene for donation of vaccine and the Kids of NYU foundation for financial support.
- Accepted January 30, 2007.
- Address correspondence to Shetal I. Shah, MD, 130 Post Ave, Suite 418, New York, NY 11590. E-mail:
The authors have indicated they have no financial relationships relevant to this article to disclose.
- Neuzil KM, Zhu Y, Griffin MR, et al. Burden of interpandemic influenza in children younger than 5 years: a 25-year prospective study. J Infect Dis.2002;185 :147– 152
- ↵Rennels MB, Mesissner HC, Committee on Infectious Diseases. Technical report: reduction of the influenza burden in children. Pediatrics2002;110(6) . Available at: www.pediatrics.org/cgi/content/full/110/6/e80
- Bernstein DI, Zahradnik JM, DeAngelis CJ, Cherry JD. Clinical reactions and serologic responses after vaccination with whole-virus or split-virus influenza vaccines in children aged 6 to 36 months. Pediatrics.1982;69 :404– 408
- ↵Cohen G, Nettleman M. Economic impact of influenza vaccination in preschool children. Pediatrics.2000;106 :973– 976
- ↵Committee on Infectious Diseases, American Academy of Pediatrics. Reduction of the influenza burden in children. Pediatrics.2002;110 :1246– 1252
- ↵Hemingway C, Poehling K. Change in recommendation affects influenza vaccinations among children 6 to 59 months of age. Pediatrics.2004;114 :948– 952
- ↵Willis B, Ndiaye S, Hopkins D, Shefer A, Task Force on Community Preventive Services. Improving influenza, pneumococcal polysaccharide, and hepatitis B vaccination coverage among adults aged <65 at high risk: a report on recommendations of the Task Force on Community Preventive Services. MMWR Recomm Rep.2005;54 :1– 11
- ↵Shah S, Caprio M, Hendricks-Munoz K. Survey of vaccination rates in NICU parents during the 2003–04 influenza season. Presented at: annual meeting of the Society for Pediatric Research; May 24–28, 2005; Washington, DC
- Copyright © 2007 by the American Academy of Pediatrics